LICENSE AGREEMENTS (Details) € in Thousands		1 Months Ended			3 Months Ended				12 Months Ended
	Jul. 30, 2020 USD ($)	Sep. 30, 2016 USD ($)	Aug. 31, 2016 USD ($)	Jun. 30, 2016 USD ($) option	Mar. 31, 2021 USD ($)	Mar. 31, 2021 EUR (€)	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)
Organization And Basis Of Presentation [Line Items]
Royalty rate					2.00%
License revenue					$ 4,310,000			$ 0
Provision for income taxes					288,000			$ 0
Transaction price							$ 11,200,000		$ 11,200,000
Qilu Pharmaceutical Co., Ltd. | Licensing Agreements
Organization And Basis Of Presentation [Line Items]
Potential milestone payments					23,000,000
Cash payment	$ 12,000,000								12,000,000
Total milestone payments	$ 23,000,000
Royalty payment based on annual net sales	12.00%
License revenue					2,800,000		$ 11,200,000
Milestone payment					3,000,000
Outstanding payments					$ 2,800,000
University of Zurich
Organization And Basis Of Presentation [Line Items]
License agreement, royalty on net product sales, percentage					4.00%	4.00%
License agreement, rate requiring reduction in the amount of royalties owed					10.00%	10.00%
License agreement, royalty on net product sales, minimum					2.00%	2.00%
Expenses related to achievement of development milestone									300,000
University of Zurich | Collaborative Arrangement, Revenue Based on Clinical Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone					$ 500,000
Micromet AG
Organization And Basis Of Presentation [Line Items]
License agreement, royalty on net product sales, percentage					3.50%	3.50%
Expenses related to achievement of development milestone					$ 600,000	€ 500			900,000	€ 700
Potential milestone payments					$ 2,800,000	€ 2,400
License Agreement, royalty payment, reduction, conditions not met					1.50%	1.50%
License maintenance fees					$ 58,625	€ 50
XOMA Ireland Limited
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone					$ 250,000
License agreement, royalty on net product sales, percentage					2.50%	2.50%
License agreement, rate requiring reduction in the amount of royalties owed					50.00%	50.00%
License agreement, royalty on net product sales, minimum					1.75%	1.75%
Roche
Organization And Basis Of Presentation [Line Items]
Up-front license fee			$ 7,500,000
Additional up-front fee			262,500,000
License agreement, option periods | option				2
License agreement, buyout amount under first option period				$ 135,000,000
License agreement, period to pay buyout option once exercised				30 days
License agreement, buyout amount under second option period				$ 265,000,000
License agreement, buyout amount under second option period, upon non-issuance of patent rights or licensed product				$ 220,000,000
Roche | First Indication
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			197,500,000
Roche | Collaborative Arrangement, Revenue Based on Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			72,500,000
Roche | Collaborative Arrangement, Revenue Based on Regulatory Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			50,000,000
Roche | Collaborative Arrangement, Revenue Based on Commercialization Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			75,000,000
Roche | Collaborative Arrangement, Revenue Based on Development Milestone, Phase II
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone			$ 20,000,000.0
Roche | Second Indication
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone					$ 65,000,000
Roche | EBI-031 | Minimum
Organization And Basis Of Presentation [Line Items]
Royalty rate					7.50%
Roche | EBI-031 | Maximum
Organization And Basis Of Presentation [Line Items]
Royalty rate					15.00%
Roche | EBI-031 | Collaborative Arrangement, Revenue Based on Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		$ 22,500,000
Roche | IL-6
Organization And Basis Of Presentation [Line Items]
Royalty rate					50.00%
MENA License Agreement | Licensing Agreements
Organization And Basis Of Presentation [Line Items]
Cash payment									3,000,000
Provision for income taxes					$ 300,000
Transaction price									$ 1,500,000